Merge pull request #3190 from donandren/issues/3188

Fix occasional exception in tooltip

src/Avalonia.Controls/ToolTipService.cs

@@ -1,6 +1,7 @@
 using System;
 using Avalonia.Input;
 using Avalonia.Threading;
+using Avalonia.VisualTree;
 
 namespace Avalonia.Controls
 {
@@ -79,7 +80,10 @@ namespace Avalonia.Controls
         {
             StopTimer();
 
-            ToolTip.SetIsOpen(control, true);
+            if ((control as IVisual).IsAttachedToVisualTree)
+            {
+                ToolTip.SetIsOpen(control, true);
+            }
         }
 
         private void Close(Control control)

tests/Avalonia.Controls.UnitTests/ToolTipTests.cs

@@ -0,0 +1,109 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.Reactive.Disposables;
+using Avalonia.Platform;
+using Avalonia.Threading;
+using Avalonia.UnitTests;
+using Avalonia.VisualTree;
+using Moq;
+using Xunit;
+
+namespace Avalonia.Controls.UnitTests
+{
+    public class TolTipTests
+    {
+        private MouseTestHelper _mouseHelper = new MouseTestHelper();
+
+        [Fact]
+        public void Should_Not_Open_On_Detached_Control()
+        {
+            //issue #3188
+            var control = new Decorator()
+            {
+                [ToolTip.TipProperty] = "Tip",
+                [ToolTip.ShowDelayProperty] = 0
+            };
+
+            Assert.False((control as IVisual).IsAttachedToVisualTree);
+
+            //here in issue #3188 exception is raised
+            _mouseHelper.Enter(control);
+
+            Assert.False(ToolTip.GetIsOpen(control));
+        }
+
+        [Fact]
+        public void Should_Open_On_Pointer_Enter()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var window = new Window();
+
+                var target = new Decorator()
+                {
+                    [ToolTip.TipProperty] = "Tip",
+                    [ToolTip.ShowDelayProperty] = 0
+                };
+
+                window.Content = target;
+
+                window.ApplyTemplate();
+                window.Presenter.ApplyTemplate();
+
+                Assert.True((target as IVisual).IsAttachedToVisualTree);
+
+                _mouseHelper.Enter(target);
+
+                Assert.True(ToolTip.GetIsOpen(target));
+            }
+        }
+
+        [Fact]
+        public void Should_Open_On_Pointer_Enter_With_Delay()
+        {
+            Action timercallback = null;
+            var delay = TimeSpan.Zero;
+
+            var pti = Mock.Of<IPlatformThreadingInterface>(x => x.CurrentThreadIsLoopThread == true);
+
+            Mock.Get(pti)
+                .Setup(v => v.StartTimer(It.IsAny<DispatcherPriority>(), It.IsAny<TimeSpan>(), It.IsAny<Action>()))
+                .Callback<DispatcherPriority, TimeSpan, Action>((priority, interval, tick) =>
+                {
+                    delay = interval;
+                    timercallback = tick;
+                })
+                .Returns(Disposable.Empty);
+
+            using (UnitTestApplication.Start(TestServices.StyledWindow.With(threadingInterface: pti)))
+            {
+                var window = new Window();
+
+                var target = new Decorator()
+                {
+                    [ToolTip.TipProperty] = "Tip",
+                    [ToolTip.ShowDelayProperty] = 1
+                };
+
+                window.Content = target;
+
+                window.ApplyTemplate();
+                window.Presenter.ApplyTemplate();
+
+                Assert.True((target as IVisual).IsAttachedToVisualTree);
+
+                _mouseHelper.Enter(target);
+
+                Assert.Equal(TimeSpan.FromMilliseconds(1), delay);
+                Assert.NotNull(timercallback);
+                Assert.False(ToolTip.GetIsOpen(target));
+
+                timercallback();
+
+                Assert.True(ToolTip.GetIsOpen(target));
+            }
+        }
+    }
+}